rpcbind man page

The rpcbind utility is a server that converts RPC program numbers into universal addresses. It must be running on the host to be able to make RPC calls on a server on that machine.

When an RPC service is started, it tells rpcbind the address at which it is listening, and the RPC program numbers it is prepared to serve. When a client wishes to make an RPC call to a given program number, it first contacts rpcbind on the server machine to determine the address where RPC requests should be sent.

The rpcbind utility should be started before any other RPC service. Normally, standard RPC servers are started by port monitors, so rpcbind must be started before port monitors are invoked.

When rpcbind is started, it checks that certain name-to-address translation-calls function correctly. If they fail, the network configuration databases may be corrupt. Since RPC services cannot function correctly in this situation, rpcbind reports the condition and terminates.

Run in debug mode. In this mode, rpcbind will log additional information during operation, and will abort on certain errors if -a is also specified. With this option, the name-to-address translation consistency checks are shown in detail.

Specify specific IP addresses to bind to for UDP requests. This option may be specified multiple times and is typically necessary when running on a multi-homed host. If no -h option is specified, rpcbind will bind to INADDR_ANY, which could lead to problems on a multi-homed host due to rpcbind returning a UDP packet from a different IP address than it was sent to. Note that when specifying IP addresses with -h, rpcbind will automatically add 127.0.0.1 and if IPv6 is enabled, ::1 to the list.

“Insecure” mode. Allow calls to SET and UNSET from any host. Normally rpcbind accepts these requests only from the loopback interface for security reasons. This change is necessary for programs that were compiled with earlier versions of the rpc library and do not make those requests using the loopback interface.

Cause rpcbind to change to the user daemon as soon as possible. This causes rpcbind to use non-privileged ports for outgoing connections, preventing non-privileged clients from using rpcbind to connect to services from a privileged port.